This invention relates to straining valves.
Freeman U.S. Pat. No. 780,334 describes a self-cleaning straining valve in which a filter mounted on a plug is rotated 90.degree. so as to be backflushed and thereby cleaned by incoming fluid. In Crocker U.S. Pat. No. 229,384 the filter has two parallel screens, and cleaning is again done by back-flushing after rotating the filter 180.degree.. In Smith U.S. Pat. No. 3,348,694 the filter is a vertical, cut away cylindrical screen, open at its ends, and cleaning is also performed by backflushing, but with fluid added from outside the fluid line. It would be desirable to retain this backflushing feature in a self-cleaning straining valve while at the same time providing a further means for cleaning the filter by passing fluid across its clogged face.